<p>The authors consider a new class of special ternary logic functions: the P-functions capable of correcting input failures, based on the regular ternary logic. There are three major results. First, the P-functions are a special subset of the regular functions with no information loss. Second a ternary logic function defined by the all-prime-implicant disjoint of any Boolean connective is a P-function. Third, a P-function may be identified from the irredundant disjunctive form. The relationship between P-functions and other meaningful ternary logic functions is discussed.</p>